This is the most important step of the analysis. Once you use the automated peak detection tools in Acqknowledge, you have to visually inspect your data from beginning to end, identify missing/duplicate/incorrect markers, and modify the markers accordingly. You cannot extract data (heart rate, breathing rate, blood pressure) from channels that have incorrect marker placement, or else your numbers will not reflect the participant’s physiology.
While the procedure of button clicks and options to run an automated peak detection differs between channels, the software is not infallible and errors occur more often than not.
For example, even if only one marker for exhalation is missing, your output spreadsheet will be entirely off, since now you have 15 inhales followed by exhales, then 2 inhales in a row and another 30 inhales followed by exhales. The first of the lonely inhales will be particularly long, artificially increasing your mean inspiration time, while the balance between the number of inhalations and exhalations and the timing is additionally off.
For heart rate, missing an R-peak means that your R-R interval in that place is double the duration than all others. If you have 2 markers for R peaks on one R-peak, you have an additional R-R interval of zero. Both cases ruin the mean and they rarely occur in isolation.